Propulsion device having circular array of inclined airfoil elements with radially-inwardly directed vacuum-inducing surfaces

ABSTRACT

A propulsion device comprises a circular series of inclined airfoil elements. Each airfoil element is connected along its lower side to a rigid plate member, which is adapted to be rotated at high speed via a motor output shaft. The airfoil elements are oriented on the plate such that their vacuum-inducing surfaces face upwardly and inwardly of the circular series, and their pressure surfaces face downwardly and outwardly of the circular series.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to propulsion devices, and moreparticularly to a device in which a novel configuration of airfoilelements is provided, in an inclined circular array.

2. Description of the Prior Art

In U.S. Pat. Nos. 5,137,424 and 5,213,474 of the present inventor, thediscovery of important fluid dynamic principles has been embodied invarious pump designs, to improve the movement of a fluid through a body.Similarly, in the present inventor's U.S. Pat. No. 5,104,541, whichissued from a divisional application of the above-mentioned U.S. Pat.No. 5,137,424, the fluid dynamic principles are embodied in an oil-waterseparator. In the present application, these principles are embodiedsomewhat differently, to improve the movement of a body through a fluid.

More directly, the present invention constitutes an improvement on and adeparture from the VTOL craft described in the present inventor'searlier U.S. Pat. No. 5,102,066. In that patent, a propeller unitcomprising a circular series of horizontally-disposed airfoil elementswas mounted on a double-shell structure, such that the airfoil elementsoccupied the annular space defined by the bottoms of the twin shells.

It has now been recognized, however, that the VTOL of the inventor'searlier patent described above has the disadvantage that the vacuumcreated within the double-shell structure creates not only a lift on theunderside of the craft, but also a downward force on the upper surfacesof the double-shell structure, which tends to neutralize the lift.

SUMMARY OF THE INVENTION

The present invention thus provides a new type of propulsion device inwhich the inventor's airfoil principles are more successfully embodied,in a manner that the propulsion induced on a craft embodying the deviceis not counteracted by undesired opposing forces. In particular, thepresent invention relates to a propulsion device in which the propellerstructure comprises a circular series of inclined airfoil elements, withthe vacuum surfaces of the airfoil elements facing inwardly and upwardlyof the series, and the pressure sides of the airfoil elements facingdownwardly and outwardly of the series.

As noted above, the airfoil elements are arranged in a circular series,and moreover are joined by a rigid plate member at that side of theairfoil elements where the leading and trailing edges converge. Theplate member is in turn connected to the output shaft of a motorconfined within a motor housing. The output shaft of the motor iscoaxial with the circular series of airfoil vanes, and so as to rotatethe circular series of vanes at a high speed in a predetermineddirection of rotation.

The downwardly and outwardly directed pressure surfaces of the airfoilvanes together define interrupted segments of a conical section, suchthat during rotation of the propulsion device, the rapidly rotatingseries of vanes appears to be an inverted truncated cone.

As each of the airfoil elements is moved through air or water uponrotation of the propeller structure, there is created a reduced pressureon its upwardly inwardly directed surface, and a higher pressure on itsdownwardly and outwardly directed surface, as is known in the art forconventional airfoils. Within the structure according to the invention,the lower pressure regions on the inner surfaces of the airfoil elementsserve to generate a region of reduced pressure within the circularseries of vanes and above the propeller structure, such that thepropulsion device, and any craft to which it is attached, tends to bedisplaced axially of the motor shaft, toward the region of inducedvacuum.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in greater detail with reference tothe accompanying drawings, which show a preferred embodiment accordingto the invention, and in which:

FIG. 1 is an axial section through a propulsion device according to apreferred embodiment of the invention; and

FIG. 2 is a plan view of the propulsion device of FIG. 1, the sectionalview of FIG. 1 having been taken along the line A--A of FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to FIG. 1 of the drawings, shown therein is a propulsiondevice according to a preferred embodiment of the invention, designatedgenerally as 1. The device 1 comprises a lower motor housing 2, whichcontains a motor or other prime mover shown schematically at 3. Themotor housing 2 comprises a bracket 4 by which the propulsion device maybe mounted to an aircraft or marine or submarine vessel.

As also shown in FIG. 1, the motor 3 comprises an output shaft 5extending upwardly from the housing 2. The motor shaft 5 may be drivendirectly by motor 3, or by suitable transmission gearing not shown.

As shown in FIG. 2, the propeller structure of the propulsion deviceaccording to the invention comprises a circular series of airfoilelements 6, arranged such that they all face in the same direction abouta circle. In particular, each of the airfoil elements comprises aleading edge 7 and a trailing edge 8, such that the propeller assemblyaccording to the invention would be rotated counterclockwise as viewedin FIG. 2.

Of course, the FIG. 2 depiction of counterclockwise rotation isarbitrary, in the sense that a mirror image of the FIG. 2 structure,which would therefore rotate in the clockwise direction, would beequally as effective. Indeed, on aircraft or marine or submarine vesselswhere it is desired to position at least one of the propulsion devicesaccording to the invention on each side of the craft, it would be usefulto have the port devices rotating clockwise, and the starboard devicesrotating counterclockwise, or vice versa, thereby to counteract torquedeveloped by the individual devices.

The airfoil elements 6 are connected to the motor output shaft 5 via arigid plate 9 and a mounting bracket 10.

FIG. 2 shows plate 9 as an imperforate disc. However, it is possible toform openings in plate 9 for the purpose of reducing its weight,provided only that such openings, when disc 9 is rotated, do notsignificantly disrupt the intended action of the airfoil elements 6.Likewise, it is possible to form disc 9 as an annular member having arelatively large central opening, in which case a hub member withradially diverging spokes would be needed to interconnect motor shaft 5and plate 9.

The airfoil elements 6 according to the invention may be constructed asshown in the inventor's earlier U.S. Pat. No. 3,734,640, the entirety ofwhich patent is hereby expressly incorporated by reference. In thatpatent, it was found that by securing similarly shaped airfoil elementsto a rigid plate, at that side of the airfoils where the leading andtrailing edges diverge, an improved rotor could be produced for acentrifugal pump having a correspondingly shaped housing.

In the present invention, it has been most surprisingly discovered that,by mounting similarly-shaped airfoil elements to a rigid rotary plate,at that side of the airfoil elements where the leading and trailingedges converge, a propulsion device is created that generates a powerfulvacuum force tending to displace the propulsion device toward thevacuum, axially of the motor shaft and toward the base of the truncatedcone described by the circular series of airfoil elements.

Although the number of airfoil elements 6 is four in this embodiment, itwill be appreciated that the number of airfoil elements may be varied atwill as a design consideration, from a minimum of two up to a maximum ofany desired number. In practice, the propeller assembly will ordinarilyhave at least three airfoil elements 6. Moreover, the fewer airfoilelements 6, the greater will be their arcuate extent, as a general rule.

FIG. 1 shows that the lower side 11 of each airfoil element is securedto the periphery of disc 9, by a suitable securing means such as bolts,not shown.

Although FIG. 1 shows motor 3 disposed below disc 9, it will beappreciated that the motor 3 is not necessarily so disposed. Instead, itcan be positioned above disc 9, provided its position does not disruptgeneration of vacuum radially inwardly of the airfoil elements 6.Likewise, by use of one or more universal joints, the motor could bepositioned to the side of the propeller structure, with reference to theorientation shown in FIG. 1.

As the disc 9 is rotated at high speed by shaft 5, the circular seriesof airfoil vanes 6 will be subject to strong centrifugal forces. Thus,to prevent the propeller structure from flying apart, it is preferred toprovide some connection means at the upper sides 12 of the airfoilelements. FIG. 2 shows such means in the form of connecting rods 14which are attached the upper sides 12 of the airfoil elements, in thevicinity of the leading edges 7 of the airfoil elements, where it iscontemplated that the centrifugal forces will be greatest.

Depending on the application of the propulsion device according to theinvention, the braces exemplified by connecting rods 14 may or may notbe necessary. Where they are considered desirable or necessary, theyneed not necessarily be attached as shown in FIG. 2. Instead, braces canbe attached to the airfoil element 6 in the most propitious location, aswill be apparent to those skilled in the art, taking into account theconsiderations of balance, strength and excess weight.

Each of the airfoil elements 6 comprises a vacuum surface 16 which, asshown in FIGS. 1 and 2, is directed inwardly and upwardly of the overallpropeller structure.

Similarly, each airfoil element 6 comprises a pressure surface 15, onthe side of the airfoil element opposite the vacuum surface 16, whichpressure surface 15 is directed downwardly and outwardly of the circularseries of airfoil elements 6.

Although the pressure surfaces 15 of the airfoil elements 6 are notfully visible in FIGS. 1 and 2, it will be appreciated that the surfaces15 collectively describe a cone that is coaxial with the output shaft 5of motor 3.

It will be appreciated that the airfoil sections 6 according to theinvention can usefully be adapted from the airfoil elements described ingreater detail in the present inventor's earlier U.S. Pat. No.3,734,640, as discussed above.

As shown in FIG. 5 and described at column 2, lines 22-56 of thatpatent, each of the airfoil sections has a region of greatest thicknessdisposed substantially nearer to the leading edge of the element thanthe trailing edge, and the radially-inwardly directed surfaces of theelements traverse the entire radial extent or thickness of the vane,from the region of greatest thickness to the trailing edge.

In operation, the motor 3 of propulsion device 1 is actuated by anoperator of the aircraft or marine vessel to which the device 1 isattached, whereupon the output shaft 5 is caused to rotate at highvelocity. This in turn causes rotation of the disc 9 and attachedairfoil elements 6, via connection 10, in the counterclockwise directionas shown in FIG. 2.

As air or water passes across the rotating series of airfoil elements 6,regions of reduced pressure are generated in the vicinity of the vacuumsurfaces 16, which reduced pressure is lower than the pressure existingon the pressure surfaces 15. As the pressure surfaces 15 are directeddownwardly and outwardly of the overall propeller structure, the regionof vacuum generated within the cup-shaped shape defined by airfoilelements 6 and disc 9, induces the propulsion device and the craft towhich it is attached to move upwardly, with reference to FIG. 1, orforwardly, if the propulsion device is positioned with plate 9perpendicular to the horizontal.

In this regard, it has been found that the inclined orientation of theairfoil element 6 according to the invention provides much betterpropulsion characteristics than would a series of horizontally disposedairfoil elements, because in the case of inclined elements the generatedreduced pressure is more or less confined within the conical regiondescribed by the rotating series of vanes. Moreover, in addition to thevertically upward lift/propulsion components acting on pressure surfaces15, it has been found that the high pressure acting laterally onsurfaces 15 produces a "squeezing", or compression, effect on theconical propeller assembly, which also contributes to the upwarddisplacement of the device 1, with reference to FIG. 1.

Accordingly, it will be appreciated that the airfoil elements 6according to the invention should be neither horizontally nor verticallydisposed, but rather should be inclined in an intermediate obliqueposition. In the embodiment described, the airfoil elements 6 areinclined at an angle of about 45°, as shown in FIG. 1; however, it willbe appreciated that this angle can be varied to vary the propulsioncharacteristics of the device, as a matter of routine optimization. Forexample, it is contemplated that an inclination angle for the airfoilelement 6 of about 30° relative to the horizontal, will producedesirable propulsion characteristics.

FIG. 2 shows each of the airfoil elements 6 with an approximately 0°angle of attack. That is, the leading edge 7 of each airfoil element isdisposed at about the same radial distance from the center of disc 9 asits respective trailing edge 8. According to the invention, it is alsoto be understood that each airfoil element 6 may be fixed in apredetermined position such that the nose of each element, comprisingleading edge 7, is positioned more radially inwardly of its respectivetrailing edge 8, as shown in FIG. 5 of U.S. Pat. No. 3,734,640. Thiswill serve to give the airfoil elements 6 a positive angle of attack.The degree of the positive angle of attack, departing from the 0 angleshown in FIG. 2, may be varied as a matter of routine designconsideration by those skilled in the art, to produce the most desirablelift/propulsion characteristics for the particular application of theinvention.

It will also be appreciated by those skilled in the art that the variousstructural components depicted in FIGS. 1 and 2 may advantageously beformed from aluminum or other suitable aircraft-grade materials, orsuitable materials for fabrication of marine or submarine vessels, andthat the choice of materials will be dictated by the particularapplication of the propulsion device built according to the invention.

While the present invention has been described in connection withvarious preferred embodiments thereof, it will be understood by thoseskilled in the art that these embodiments have been given solely forpurposes of illustration, and should not be construed as limiting inanyway the true scope and spirit of the invention as set forth in theappending claims.

What is claimed is:
 1. A propulsion device comprising a circular series of airfoil elements, each airfoil element comprising a leading edge, a trailing edge, and a pair of generally parallel upper and lower edges interconnecting said leading edge and trailing edge, each airfoil element being mounted via its lower edge to a rigid interconnecting member, each airfoil element having a pressure surface and an opposed vacuum-inducing surface, said airfoil elements being inclined such that the vacuum-inducing surfaces of the airfoil elements face upwardly and inwardly of said circular series, and the pressure surfaces of said airfoil elements face downwardly and outwardly of the circular series, each airfoil element having a region of greatest thickness located substantially nearer its leading edge than its trailing edge, and each said vacuum-inducing surface traversing the entire radial extent of its airfoil element from said region of greatest thickness to said trailing edge, said leading and trailing edges of each airfoil element converging toward said lower edge and diverging toward said upper edge; said circular series of airfoil elements and said interconnecting member collectively describing a generally cup-shaped structure being open at the upper edges of said airfoil elements; and a motor output shaft being centrally attached to said rigid interconnecting member and extending perpendicularly therefrom.
 2. The propulsion device according to claim 1, wherein each of said airfoil elements is inclined relative to said plate member at an angle of about 45°.
 3. The propulsion device according to claim 1, wherein each of said airfoil elements is inclined relative to said plate member at an angle of about 30°.
 4. The propulsion device according to claim 1, wherein said rigid plate is an imperforate circular disc.
 5. The propulsion device according to claim 1, further comprising bracing members interconnecting adjacent airfoil elements in said circular series.
 6. The propulsion device according to claim 5, wherein said bracing members are rod-shaped elements attached to said upper edges of said airfoil elements.
 7. The propulsion device according to claim 1, wherein the leading edge of each airfoil element is disposed radially outwardly of said circular series at about the same distance as its respective trailing edge.
 8. The propulsion device according to claim 1, wherein the leading edge of each airfoil element is positioned radially outwardly of said circular series at a distance less than its respective trailing edge. 